Float valve for fuel systems



De 18, 1951- D. SAMIRAN FLOAT VALVE FOR FUEL SYSTEMS Original Filed Dec Patented Dec. 18, Y1951 v FLOAT VALVE Fon FUEL SYSTEMS,

David Samiran, Fort Wayne, Indi 7 original application December 17, 194s,.seria1No. 651,952.. Dividedand thisI application. December 2s19.49,.s9ria1 No. 135,473 v 2 claims. (o1. 137-104)v Granted under the. act ofMarch. 3,. 1883,. as.

' They-invention relatesl broadly .to a oat valve.

adapted. to stop: inilow` of fuel; into atank at a predetermined level".

Float-valves ofthe class to `which this inven-l tion relates are-'necessarily of large flow capacity,- and, order thatA a relatively small float may operate so large-a valve, ari-small bleed valve is provided andarranged to be operatedy by the float todirecta. portionof; the pressurized fuel whichisentering the` tank into a chamber where it is arranged toract4 againstI a` large diaphragmf area` to` open the main valve. l

More specircally the invention` comprisesY hydran-lic means whereby, when the tank becomes filled, and. the .iloat closes against further inow, itis hydraulically locked in the` closed posiamended April 30, 1928; 37.0 0.. G. '757),

y the metall washers 36 and 40. Parts 34, 2li,V 36;

tionuntil. the;` tanlnis` completely emptied and refueling of thetanlg:` is. again undertaken..

The obiect; of the` invention is toY provide a float.- valve, of this kind which isof simple construction: and inexpensive-.yet highly veffective for the purpose: intended I attain this object in the. device hereinafter described. andY illustrated in.` the tufawings, wherein,Y the single ligure of the. drawing` is arvertical axial sectiony througha oat: valve made accordance with this inventionsupported Ain the top of` a fuel tank of anaircraft.-

The single ligure of the drawing. 'is acut away view showing4 the main valve and its float controlpilotA valve, the locking'member for. the float andthe float controlled release member forl the loch.4 Y

The ioat valve shown in the tank 20' in the drawing. comprises a. lower housing part 22 and an upper housing part 24 clamped together by any suitable means (none shown)` withv the outer edge of a diaphragm 23 clampedbetween the two housing-parts.. Y A

The fuel inlet pipe. '2ldelivers fuel intof the chamber 23I withirr thefhub Sit which carries the seat. 32 ofthe main valve 29. The centrali portionl of the, flexible diaphragm 2E lies between meta-l.I washers Mandi 36;. The flexible disc 38 which engagesr'the valve seat: 32? lies between` 38` and. 40 are all provided with a centralopening which fits over' the cup 42. Cup 42 has a slight shoulder near' the lower end and is ex.- ternally threaded near the top for the nut 44 by which the parts 34', 26:-, 36, 38 and 40 are clamped together.k

Surrounding the hub 30 is an annular chamber 4d with circumferentially spaced windows' 48, whereby, when the disc 38 is raised off the seat 32', fuel may flow from the chamber 28 over the seat 32' into the annular space 46 and out the windows 48 into' the fuel tank 20 w Movable vertically in the cup 42 is an inverted stepped cup 5U. A coilspring- 49 rests on a shoulderr ofthe cup 5u forcing it to theV bottom of cup 42.' and therebyholding the main valve disc 3-8 lightly on lthe seatv 32. A small check valve broadly designated by the numeral 5t ,corr-A sists of a disc 52 whiclr lies over afsmall hole 54 in; the bottomof the cup 42 and is held thereon by a.. light spring. 56. `The disc 52 is limited` in upward movement by engagement' w-ithftho.y shoulder inthe invertedl cup 50. A pressure chamber 58, is formed by recessing the bottom of the upper housing part 24 whereby, whenever the'check valve disc 52 is raised by the pressure inr chamber 23 until the pressure equalizes` asbetween the chambers 28 and .58; the main valve disc 38 will be held Vtightly on:y they seat 32 by reason of the fact that, although the p. s. if. in both chambers is the same, the area of the. chamber 58- greatly exceeds thearea. of the chamberZ, l

Hingedly'supported in the upper housing part 24 is` afloat comprising a cork block 60, rein.- forced by metal plates 52 and 54 held to the block by bolts 56 and- 68.. Plate 64 has the edgesturned downward-,to provide bearing forv the hinge pin. 10; Y

'IFightl-yy xed inI the upper housing part 24 is ableed valvel-I `hav-ing a casing 12 containing aneedle-valve stem. 142 which -isguided at the upperend in the casing; An adjusting screw 16- passes through a holein thermetalh plate-.Minto the top of thev valve stem 14. A lock nut 1191 on the screw 16 maintains proper adjustment between the float and theneedle valve.A The iow capacity of the needle valve should be-con-A siderably in excess: of theV ow capacity of the check valve. opening 54.4 Dropping of the iloat block` Si! from the. position shown opens the needle valve T4 whereby fuel under pressure may escapefrom the chambert faster than it mayy enterthrouglr the checkvalveropening 54, where--v by the pressure in the chamber 58 drops, and fuel supplied by the pipe 21 will pass over the valve seat 32 into the annular space 46, through the windows 48 into the tank 20.

The hydraulic lock which has kbeen broadly designated by the numeral 81 consists of a casing 82 supported on the upper housing part 24 and having acover 84 fastened to the casing by means not shown with a gasket 86 and the flange 8,8 of a bellows 90 held between the casing and cover. A rod 92 is fast to the inside of the lower closed end of the bellows 90 andhas bearing in the cover 84 for vertical sliding movement. A flexible disc 94 is fast on the outside of the lower closed end of the bellows. A coil spring 96 urges axial extension of the bellows. An arm 98 carries an adjusting screw the end of which rests on the outer end of the float reinforcing plate 64, whereby, when the bellows is fully extended and the flexible disc 94 seated, the float will be held locked in the up position as shown. A lock nut I02lmaintains the adjustment of the screw |00.

A passageway |04 connects the space |06 around'the outside' of the bellows 90 by way of the pipe 23 or by way of the pipe |08 to the inlet of the flow level control valve 86.

The flow level control valve 80 comprises a body VI In and cover I I2 clamped together on a gasket |I4. A float ||6 is carried on an arm I I8 pivoted at |20 on a bracket |22. A sleeve ||1 fixed in the cover ||2 provides sliding bearing for the valve stemk ||9. At the lower end of the valve stem ||9 there is a valve head |2I.Y When the tank 20 is less than full, and the float IIG consequently lowered from the position shown, the valve head assumes its raised position wherein it seats and closes the opening |24 against further flow of fuel coming through the pipe I 08, chamber |26 and opening |25.

Assuming that the tank 20 is empty and that fuel is to be brought in through the pipe 21, the operation oi.' the float valve herein disclosed is substantially as follows: v

When a tank 20 is empty and about to be refueled, the float valve mechanism herein disclosed will appear as shown in the drawing, i. e., main float 60 up, main valve 29 closed, hydraulic lock 81 in the float locking position, the auxiliary float I|6 down whereby the auxiliary float valve 86 is closed.

' When'the incoming fuel under pressure is admitted to the pipes 21 and 23 it cannot immediately enter the tank through the pipe 21 because the main valve 29 is locked in the closed position by the hydraulic lock 81. The pressurized fuel, however, enters the hydraulic lock 81 by way of the smaller pipe 23, and flows through the pipe |08 into the auxiliary float valve 0B which is now closed, whereby the pressurized fuel builds up in the chamber |06 thereby collapsing the bellows 90 against the resistance of the spring 96 and thereby unlocking the hydraulic lock 81 so that the main float 60 may drop and open the needle valve 1|, therebv relievingr the pressure in chamber 58 whereby the main valve 29 opens and `fuel will flow into the tank through the main supply pipe 21.

Fluid flow into the tank 20 will now continue through the main supply pipe 21 until the main float 60 rises and operates the needle valve 1| to pressurize the chamber 58 to close the main valve 29. Simultaneously the auxiliary float H6 rises and opens the auxiliary valve 2| which bleeds pressurized fuel out of the chamber |06 and allows the spring 90 to set the hydrauli lock 81 to again lock the main float 60 in the up position and the main valve 29 in the closed position where it will remain until the next'refueling of the tank takes place.

From the foregoing it is clear that where one of a series of tanks, each using a mechanism according to this invention, becomes filled, and

' the main valve closes against further inflow, it

will not open again merely because fuel is withdrawn from the tank but will open only when refueling is initiated, which, in the normal course of operation is when the tanks become empty.

The invention is particularly appropriate in a combined fuel servicing and fuel feeding system where all1 tanks receive fuel from and feed fuel through a common source since, when any tank is empty it is self isolated from the remainder of the system until all tanks are empty and refueling is initiated.

Having described my invention, I claim:

1. In an aircraft fuel system, a tank, a fuel intake shut-oil' mechanism which consists of a y housing, a main valve in said housing comprising a main valve seat, a main valve disc adapted to be pressed upon said seat to stop fluid flow from the inflow to the outflow side of said main valve, a pressure chamber above said disc adapted to be filled with fluid under pressure to press said disc onto said seat, a small check valve biased for one-way flow from the inflow side of the main valve to said pressure chamber, a bleed valve having flow capacity greater than said check valve connecting said pressure chamber back to said tank, a main float movably supported in said housing and adapted, in a raised position, to close said bleed valve and in a lowered position to open said bleed valve, a hydraulic lock comprising a casing, a locking bar having sliding bearing in said casing and adapted normally to extend from said casing and hold said main float in the raised position, but movable to allow said float to assume the lowered position upon application of pressure to the inside of said casing, conduit means to convey fluid under pressure to the inside of said casing, an auxiliary float, a relief valve operable by said auxiliary float to open when the float is in the raised position and to close when the float is in the lowered position, and a passageway connecting the inside of said casing to said relief valve, whereby, when the auxiliary float is raised and the relief valve therefore open, fluid under pressure entering said casing through said conduit escapes through said relief valve and no pressure builds up in the casing and the main float therefore remains locked in the raised position until the auxiliary float assumes the lowered position whereupon the main float is unlocked and allowed to assume its lowered position.

2. The combination, in an aircraft fuel system, of a tank, a fuel intake shutoff mechanism which consists of a housing, a main valve in said housing comprising a main valve seat,` a main valve disc adapted to be pressed upon said seat to stop fluid flow through said main valve into said tank, a pressure chamber above said disc adapted, by the pressure of the incoming fuel, to press said disc onto said seat, a small slow leakage means between the inflow side of the main valve and the said pressure chamber, a'bleed valve having flow' capacity greater than said vleakage means adapted when open to connect said pressure chamber back to said tank, a main float movably supported in said housing and adapted in a raised 01. lQWered position to respectively close or open said bleed Valve, a locking means associated with said main oat including a member normally holding said main float in a raised position whereby the bleed valve is closed, but operative by pressure of incomingy fuel to move to another position to hold said main float in a lowered position whereby said bleed Valve is open, conduifJ means to convey fuel under pressure to said locking means, an auxiliary float, a relief valve operable by said auxiliary float to open 10 -when the auxiliary float is in a raised position and to close when the auxiliary oat is in a lowered position, and a passageway connecting the locking means to the relief valve, whereby,

when the auxiliary oat-is raised and the relief 15 Number valve therefore open, fluid under pressure entering said locking means through said conduit escapes through said relief Valve and no pressure `nuilcls up in the locking means and the main REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date 2,491,521 Samiran Dec. 20, 1949 

